Icinga DB: make icinga:history:stream:notification#id deterministic

... i.e. UUID -> SHA1(x..., send time) given that SHA1(x...) = notification id.
Rationale: allow both masters to write the same notification history concurrently (while
not in split-brain), so that REPLACE INTO deduplicates the same events written twice.

lib/icingadb/icingadb-objects.cpp

@@ -1603,7 +1603,7 @@ void IcingaDB::SendStateChange(const ConfigObject::Ptr& object, const CheckResul
 
 void IcingaDB::SendSentNotification(
 	const Notification::Ptr& notification, const Checkable::Ptr& checkable, const std::set<User::Ptr>& users,
-	NotificationType type, const CheckResult::Ptr& cr, const String& author, const String& text
+	NotificationType type, const CheckResult::Ptr& cr, const String& author, const String& text, double sendTime
 )
 {
 	if (!m_Rcon || !m_Rcon->IsConnected())
@@ -1620,10 +1620,15 @@ void IcingaDB::SendSentNotification(
 
 	auto usersAmount (users.size());
 	auto notificationHistoryId = Utility::NewUniqueID();
+	auto sendTs (TimestampToMilliseconds(sendTime));
+
+	Array::Ptr rawId = new Array(Prepend(GetEnvironment(), GetObjectIdentifiersWithoutEnv(notification)));
+	rawId->Add(GetNotificationTypeByEnum(type));
+	rawId->Add(sendTs);
 
 	std::vector<String> xAdd ({
 		"XADD", "icinga:history:stream:notification", "*",
-		"id", notificationHistoryId,
+		"id", HashValue(rawId),
 		"environment_id", m_EnvironmentId,
 		"notification_id", GetObjectIdentifier(notification),
 		"host_id", GetObjectIdentifier(host),
@@ -1633,7 +1638,7 @@ void IcingaDB::SendSentNotification(
 		"author", Utility::ValidateUTF8(author),
 		"text", Utility::ValidateUTF8(finalText),
 		"users_notified", Convert::ToString(usersAmount),
-		"send_time", Convert::ToString(TimestampToMilliseconds(Utility::GetTime())),
+		"send_time", Convert::ToString(sendTs),
 		"event_id", Utility::NewUniqueID(),
 		"event_type", "notification"
 	});
@@ -2382,10 +2387,11 @@ void IcingaDB::NotificationSentToAllUsersHandler(
 )
 {
 	auto rws (ConfigType::GetObjectsByType<IcingaDB>());
+	auto sendTime (notification->GetLastNotification());
 
 	if (!rws.empty()) {
 		for (auto& rw : rws) {
-			rw->SendSentNotification(notification, checkable, users, type, cr, author, text);
+			rw->SendSentNotification(notification, checkable, users, type, cr, author, text, sendTime);
 		}
 	}
 }

lib/icingadb/icingadb-utility.cpp

@@ -149,6 +149,32 @@ Dictionary::Ptr IcingaDB::SerializeVars(const CustomVarObject::Ptr& object)
 	return res;
 }
 
+const char* IcingaDB::GetNotificationTypeByEnum(NotificationType type)
+{
+	switch (type) {
+		case NotificationDowntimeStart:
+			return "downtime_start";
+		case NotificationDowntimeEnd:
+			return "downtime_end";
+		case NotificationDowntimeRemoved:
+			return "downtime_removed";
+		case NotificationCustom:
+			return "custom";
+		case NotificationAcknowledgement:
+			return "acknowledgement";
+		case NotificationProblem:
+			return "problem";
+		case NotificationRecovery:
+			return "recovery";
+		case NotificationFlappingStart:
+			return "flapping_start";
+		case NotificationFlappingEnd:
+			return "flapping_end";
+	}
+
+	VERIFY(!"Invalid notification type.");
+}
+
 static const std::set<String> propertiesBlacklistEmpty;
 
 String IcingaDB::HashValue(const Value& value)

lib/icingadb/icingadb.hpp

@@ -81,7 +81,7 @@ private:
 
 	void SendSentNotification(
 		const Notification::Ptr& notification, const Checkable::Ptr& checkable, const std::set<User::Ptr>& users,
-		NotificationType type, const CheckResult::Ptr& cr, const String& author, const String& text
+		NotificationType type, const CheckResult::Ptr& cr, const String& author, const String& text, double sendTime
 	);
 
 	void SendStartedDowntime(const Downtime::Ptr& downtime);
@@ -109,6 +109,7 @@ private:
 	static String GetObjectIdentifier(const ConfigObject::Ptr& object);
 	static String GetEnvironment();
 	static Dictionary::Ptr SerializeVars(const CustomVarObject::Ptr& object);
+	static const char* GetNotificationTypeByEnum(NotificationType type);
 
 	static String HashValue(const Value& value);
 	static String HashValue(const Value& value, const std::set<String>& propertiesBlacklist, bool propertiesWhitelist = false);